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Chemical Synthesis

Pd(0) EnCat 30NP

Introduction

Sigma-Aldrich, in collaboration with Reaxa, is pleased to offer an innovative, versatile heterogeneous nanoparticulate Pd(0) catalyst, Pd(0) EnCat™ 30NP, which displays excellent chemoselectivity under hydrogenation and transfer hydrogenation conditions. Reductive transformations catalyzed by Pd(0) EnCat™ 30NP include aryl ketones, aldehydes and epoxides to the corresponding alcohols; nitro arenes and aryl nitriles to the corresponding amines; alkenes and alkynes to the corresponding alkanes; debenzylation of aryl benzyl ethers, benzyl esters and benzyl amines; and reductive aminations.

Advantages of Pd(0) EnCat™ 30NP:     

  • Safe and non-pyrophoric      
  • Trivial removal of catalyst from reactor      
  • Very low metal contamination of product      
  • No Pd(0) contamination of reactor vessel      
  • Excellent catalyst recyclability      
  • Highly chemoselective under hydrogenation & transfer hydrogenation conditions      
  • Excellent batch-to-batch reproducibility of catalyst activity

 

Representative Applications:

Reaction examples using Pd(0) EnCat™ 30NP are sub-sectioned below. In all cases exceptionally low levels of Pd contamination (< 10 ppm) were detected in the crude product.

Hydrogenation

Chemoselective hydrogenation of aryl aldehydes, ketones and epoxides to benzylic alcohols with 100% retention of stereochemistry and very little over-reduction of sensitive benzylic alcohols.

 

Reductive aminations with selective formation of secondary or tertiary amines

Pd(0)EnCat™ 30NP offers an attractive alternative approach to reductive aminations. By controlling the number of equivalents of aldehyde, selective formation of secondary or tertiary amines is achieved to afford excellent product yields.



Reduction of aryl halides, aryl benzyl ethers, esters, amines, alkenes and alkynes1


General Conditions: H2 (balloon), 10 mol% Pd(0) EnCat™ 30NP, EtOH, rt, 16h

Transfer Hydrogenation

Pd(0) EnCat™ 30NP enables highly efficient chemoselective transfer hydrogenation of a wide range of substrates including aryl ketones, aryl aldehydes and aryl epoxides to benzyl alcohols.2 Aryl benzyl ethers, esters and amines are debenzylated whereas alkyl benzyl ethers, alkyl Cbz groups, and benzylamines are unaffected under these conditions.



Example of Catalyst Recycling:



   Product Information


Product Name Product # 
Pd(0) EnCat™ 30NP, nanoparticles: 0.4 mmol/g Pd loading 653667

 

Hydrogenation & Transfer Hydrogenation User Guide (547 KB PDF)

Pd(0) EnCat™ 30NP Commercial Availability and Technical Support

R&D quantities of Pd(0) EnCat™ 30NP are available from Sigma-Aldrich (Product Number 653667), www.sigma-aldrich.com. For technical support, bulk quotations and further information on encapsulated catalysts please contact info@reaxa.com.

References
1. Bremeyer, N., Ley, S.V., Ramarao, C., Shirley, I.M., Smith, S.C. Synlett., 2002, 11, 1843.
2. (a) Ley, S.V. et al. Chem. Comm., 2003, 678; (b) Ley, S.V., et al. Org. Lett., 2003, 5, 4665.